Superfood Highlight: Green Tea

Long known for its widespread use in Japanese culture, green tea has a wealth of health benefits. The tea is obtained from a shrub-like plant called Camellia sinensis, and contains a variety of healthful components including catechins, which are known for their anti-cancer and anti-oxidative properties. Fun fact, black tea, green tea, oolong tea and matcha all originate from this same Camellia sinensis shrub. The difference is in how they are made once the leaves of the Camellia are harvested, which then affects the taste and color of the tea. Green tea is made by taking the leaves of the Camellia plant and rapidly steaming them. As green tea has been increasingly popular in the natural health arena, many studies have been, and continue to be, conducted on the benefits of green tea, particularly as it relates to weight loss, but also its role in cardioprotection, neuroprotection and cancer prevention.

Green Tea and Weight Loss

Consuming green tea regularly may improve weight loss, decrease waist circumference, and help maintain weight after the initial weight loss. How green tea reduces weight is related to a catechin found in green tea, known as EGCG, which causes a significant increase in energy expenditure and fat oxidation, as well as by enhancing the sympathetic nervous system, a.k.a., the fight or flight response. While the parasympathetic system causes our bodies to “rest and digest,” the sympathetic system causes are bodies to work a little harder, leading to greater energy expenditure.

A study in Northern Iran was conducted with 84 participants who were classified as obese, were randomly assigned to one of two groups. The first group was asked to drink a cup of green tea after breakfast and lunch. The second group was asked to drink a cup of mineral water after breakfast and lunch. The participants were asked walk 30 minutes, three times per week and to avoid any other weight loss program during this 12 week period. All participants’ weight, waist circumference, waist to hip ratio and BMI were calculated at baseline, 8 weeks and 12 weeks. The results were significant in that the group assigned to two cups of green tea had significant improvements in waist circumference, weight, and BMI. Participants in the green tea group showed an average weight loss of 16 lbs, a decrease in waist circumference of 4cm, and a decrease in BMI from an average of 29.95 to an average of 26.85 (Bahram, et al., 2018).

Diabetes

As well as its effects on weight loss, green tea also helps in glucose regulation and can improve insulin resistance in skeletal muscles. Regular consumption of green tea in clinical trials (i.e. 2 cups/day) has shown improvements in insulin secreting ability in people with Type 2 Diabetes Mellitus, as well as improvements in Hemoglobin A1c levels (the average blood sugar level over a three month period) in those patients who don’t yet require insulin.

Green Tea Improves Cardiovascular Health

Regular green tea consumption improves blood pressure, helps lower cholesterol, and assists in the prevention of ischemic injury (i.e. heart attacks and stroke). One study in the International Journal of Cardiology revealed that green tea even showed cardiovascular benefits after a heart attack in animal studies. These benefits included improvements in both systolic (the top number) and diastolic (the bottom number) blood pressure, decreasing oxidative stress, improving mitochondrial function, and decreasing cell death in the heart.

Neuroprotection

The protective effects of green tea in the central nervous system make it a topic of study for the prevention of Alzheimer’s and Parkinson’s disease. There are many factors that play a role in nervous system degeneration, as is what happens in these two disease processes. One factor is the role of glutamate, a major neurotransmitter in the human brain. Too much of this hormone can lead to dysfunction and cell death, and can contribute to both acute and chronic neurological problems. Components in green tea known as polyphenols help to regulate glutamate, prevent against oxidative stress and decrease inflammation, which are all protective against neurological disorders. Green tea continues to be studied for its role in this field.

Cancer and Green Tea

Green tea is much debated in the scientific community as to whether it has anti-cancer benefits or not. Though many studies show green tea does not have any benefit in many types of cancer, there is some evidence that it may have a role in the prevention and treatment of both oral and breast cancers. However, many more, controlled studies need to be conducted before any conclusions can be drawn.

Though research is ongoing, it’s safe to say that green tea has promising health benefits on a variety of body systems. With high safety, and so many ways to drink it, green tea is a cost-effective way to improve your overall health when combined with a healthy lifestyle. Grab some morning or afternoon tea, eat a well-balanced diet high in colorful fruits and vegetables, low in saturated fats and processed foods, get outside for a walk in this beautiful summer weather, and be on your way to a healthier you!

My favorite way to drink green tea: fill the bottom of a glass with a small handful of frozen berries, whatever kind you like, and a teaspoon of raw, local honey. Add a green tea bag and a cup of hot water, and let the bag steep for 3-5 minutes. Take the bag out, give it a good stir, fill the cup with ice, and don’t turn your back on it or your 5-year-old will drink it all before you know it. At least that’s what happens in my house : )

If you have other green tea recipes, please share them in the comments below!

*The information on this page is not meant to replace medical advice or the quality of healthcare given from seeing a physician or nurse practitioner.

References:

Bahram, N. N., Sedighinejad, A., Haghighi, M., Farzi, F., Rimaz, S., Atrkarroushan, Z., & Biazar, G. (2018). The anti-obesity effects of green tea: A controlled, randomized, clinical trial. Iranian Red Crescent Medical Journal, 20(1) doi:http://dx.doi.org/10.5812/ircmj.55950

Lin, C., Cao, C., Cheng, Y., & Xiao-Yan, Q. (2016). Green tea polyphenols attenuated glutamate excitotoxicity via antioxidative and antiapoptotic pathway in the primary cultured cortical neurons. Oxidative Medicine and Cellular Longevity, 2016 doi:http://dx.doi.org/10.1155/2016/2050435

Lustoza, B., et al. (2016). Green tea (Cammellia sinensis) attenuates ventricular remodeling after experimental myocardial infarction. International Journal of Cardiology (v.225) p.147-153. DOI:https://doi.org/10.1016/j.ijcard.2016.09.092

Serban, C., et al. (2015). Effects of supplementation with green tea catechins on c-reactive proteins concentrations: a systematic review and meta-analysis of randomized controlled trials. Retrieved from: https://www-proquest-com.databases.library.georgetown.edu/pqrlalumni/docview/1702699290/7BC4F667F62545BDPQ/7?accountid=142883